package cn.tedu.jsd2207csmall.passport.filter;

import cn.tedu.jsd2207csmall.passport.security.LoginPrincipal;
import cn.tedu.jsd2207csmall.passport.web.JsonResult;
import cn.tedu.jsd2207csmall.passport.web.ServiceCode;
import com.alibaba.fastjson.JSON;
import io.jsonwebtoken.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;

import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * JWT过滤器
 *
 * @author java@d.cn
 * @version 0.0.1
 */
@Slf4j
@Component
public class JwtAuthorizationFilter extends OncePerRequestFilter {

    @Value("${csmall.jwt.secret-key}")
    private String secretKey;

    public static final int JWT_MIN_LENGTH=113;

    public JwtAuthorizationFilter() {
        log.info("创建过滤器对象:JwtAuthorizationFilter");
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request,
                                    HttpServletResponse response,
                                    FilterChain filterChain) throws ServletException, IOException {
        log.info("JwtAuthorizationFilter开始执行过滤");

        //清空Security上下文
        //Security上下文中的认证信息也会被清除
        SecurityContextHolder.clearContext();

        //获取客户端携带的JWT
        String jwt=request.getHeader("Authorization");
        log.info("获取客户端携带的JWT:{}",jwt);

        //检查是否获取到了基本有效的JWT
        if (!StringUtils.hasText(jwt) || jwt.length()<JWT_MIN_LENGTH){
            log.info("获取到的JWT被视为无效,当前过滤器即将放行...");
            filterChain.doFilter(request,response);
            return;
        }

        //尝试解析JWT
        log.info("获取到的JWT被视为有效,准备解析JWT.....");
        Claims claims=null;
        response.setContentType("application/json;charset=utf-8");
        try{
           claims = Jwts.parser()
                    .setSigningKey(secretKey)
                    .parseClaimsJws(jwt)
                    .getBody();
        }catch (SignatureException e){
            log.info("解析JWT是出现了SignatureException");

            String message="非法访问!!!!!";

            JsonResult<Void> jsonResult=JsonResult.fail(ServiceCode.ERR_JWT_SIGNATURE,message);

            String jsonResultString = JSON.toJSONString(jsonResult);
            PrintWriter writer = response.getWriter();
            writer.println(jsonResultString);
            return;
        }catch (MalformedJwtException e){
            log.info("解析JWT是出现了MalformedJwtException");
            String message="非法访问!!!!!";

            JsonResult<Void> jsonResult=JsonResult.fail(ServiceCode.ERR_JWT_MALFORMED,message);

            String jsonResultString = JSON.toJSONString(jsonResult);
            PrintWriter writer = response.getWriter();
            writer.println(jsonResultString);
            return;
        }catch (ExpiredJwtException e){
            log.info("解析JWT是出现了ExpiredJwtException");
            String message="登录信息已过期,请重新登录";

            JsonResult<Void> jsonResult=JsonResult.fail(ServiceCode.ERR_JWT_EXPIRED,message);

            String jsonResultString = JSON.toJSONString(jsonResult);
            PrintWriter writer = response.getWriter();
            writer.println(jsonResultString);
            return;
        }catch (Throwable e){
            log.info("解析JWT是出现了Throwable,需要开发人员在JWT过滤器补充对异常的处理");
            e.printStackTrace();
            String message="解析JWT时出现Throwable，需要开发人员在JWT过滤器补充对异常的处理";

            PrintWriter writer = response.getWriter();
            writer.println(message);
            return;
        }

        String username=claims.get("username",String.class);
        Long id=claims.get("id",Long.class);
        String authoritiesJsonString=claims.get("authoritiesJsonString",String.class);

        //处理权限信息
        List<SimpleGrantedAuthority>  authorities
                = JSON.parseArray(authoritiesJsonString,SimpleGrantedAuthority.class);

       // 创建Authentication对象
        LoginPrincipal principal=new LoginPrincipal(id,username);
        Authentication authentication=
                new UsernamePasswordAuthenticationToken(
                        principal,null,authorities);

        // 将Authentication对象存入到SecurityContext
        log.info("向SecurityContext中存入认证信息：{}", authentication);
        SecurityContextHolder.getContext().setAuthentication(authentication);

        //过滤链继续向后传递,即:放行
        log.info("JWT过滤器执行完毕,放行!");
        filterChain.doFilter(request,response);
    }
}
